SHPB tests on the dynamic characteristics of calcareous sand under repeated one-dimensional impact loading

In order to solve the problems about the calcareous sand layer in the construction of pile foundation in the South China Sea, a modified split Hopkinson pressure bar (SHPB) apparatus was used to investigate the dynamic characteristics of calcareous sand under repeated impact loading. A total of 28 times of repeated 1D impact tests were conducted to obtain the stress-strain curves, 1D compression curves and energy absorption efficiency curves of calcareous sand and silica sand, so as to explore the influences of impact times, moisture content and relative density on the dynamic characteristics of the two types of sand specimens under repeated 1D impact loading. The test results show that the dynamic apparent modulus (dynamic stiffness) of calcareous sand is approximately 10% of that of silica sand after the first impact or repeated impacts due to the difference in particle shape and mineral compositions; with repeated impacts, both sand specimens continue to be compacted, showing an increase in stiffness and a decrease in compressibility; the yield stresses of calcareous sand and silica sand under the first impact are about 3.20 MPa and 9.33 MPa respectively, and then a large number of particles begin to break, and the compression index is about 0.87 and 0.41 respectively. After repeated impacts, the yield stress of the two kinds of sand samples increases to 6.14 MPa and 12.54 MPa respectively; the energy absorption efficiency of calcareous sand is higher than that of silica sand, and the energy absorption efficiency of calcareous sand specimens with different moisture content and relative density tends to be similar after repeated impacts. © 2022 Chinese Vibration Engineering Society. All rights reserved.